Manufacture of tin plate



March 9, 1926. 1,576,274

G. M. HARRIS MANUFACTURE OF TIN PLATE Filed March 1925 Paliented Ma. 9, 1926.

UNITED STATES PATENT OFFICE.

instruments]: or am. Puma.

Application filed larch 28, 1885. Serial No. 19,188.

To all whom it may concern:

Be it known that L'GAVIN Moan Hams,

a subject of the King of England, residing at Lancashire, England, have invented cer tain new and useful Improvements in the wide and about mches long. The pieces are .then cut to the required measurements by shears, then the plates are pulled apart by hand.

The next operations are black pickhng', in which the lates are immersed in hot dilute sulphuric acid,-. andswilling,.. in which the are washed with cold runni'n water. T e plates are then sorted by ban to remove those plates which have not been sufficiently attacked by the acid.- These are returned for further pickling.

The next step in the existing method, known as black packin consists in packing the plates whlle st-il wet in piles on the annealing stands. An annealing cover (an inverted rectan lar box made of steel or wrought-iron) is placed over each pile of lates, the space between this cover and the ii of the stand bein filled withsand. The

ates are then so jected to the nown as black annealin in which the ots (stand, cover and p ates inside) are heated to, a temperature sufliciently high to ensure softening. The :pots' are removed the covers are taken off, after which the plates are thrown out b sub'ectin the piles of'plates to repeated 1') ows mm s edge ammers (or pneumatic hammers) to sofa-- e rate the plates one from another. plates are then cold rolled to im art the requisite finish to the surface. e cold I'OCBSS from the furnace and allowed to cool before rolling .hardens the plates somewhat, and

they are therefore annealed once more in the process of white annealing. his not necessary ln the second annealing to heat to so high a temperature nor for such a long time min the first.

The lates are now subjected to the process of white pickling, generally in weaker sulphuric aci than was used in the previouspickling; then they are .swilled and are lmmersed in water preparatory to tinnlng.

One feature of the present invention comprises a modification m the manufacture of tin-plate wherein black-pickling is carried out after black annealin and the plates when pickled and swille are dried at a temperature not exceeding 1003C. (preferably by absorption) and directly passed to the cold-rolling plant. Preferably the black annealingfollows directly upon the hot rollin shearing and opening operations. The 'or or of the steps of black'annealing and pickling IS-fllllS Inverted and this inversion ias many advanta 'es. All oxidation isremoved before the ate goes throughthe cold rolling process. n the old method, plates oxidized too severely. durin blackannealing had to be returned to t e pickling for the purpose of removing the oxidation, and thenre-anne'aled.

In the. ordinary process of manufacture the annealing step serves two functions; itv

not only, softens the plates, but also serves to dry them after pic rling, and'the advantage of .using the annealing step for drying is that unlike drying byheating the plates at low temperatures, serious. oxidation of the lates is avoided, at all events in the case .of t ose plates which have been subjected to suflicient superincum'bent weight tb' keep .themdpiled closetogether so that" air is exelude from the surfaces on cooling. However, the upper lates-of-the ile, which get i to be returned for b less weight on t eml, are oxi 'zed and have the ordinary ack pickling again. In I rocess they are then re-annealed. By t e. present process returns and their re-treatment can be avoided alto-y gether'. The present invention also contemplates the treatment of the returns in the ordinary process after their second black without re-annealing.

pickling, and in this case they are dried and passed directly to the cold rollin plant properties are superior to those of re-annealed plates.

, The importance of avoiding oxidation during drying is very great as otherwise the cold rolling process willroll oxide into the metal and spoil the surface. It has now been found thatin drying by evaporation oxidation tends to occur. The moisture is according to this invention removed by adsorption into a suitable absorbent medium applied to the plates. In a preferred process the plates are dried bybringmg water absorbent material into contact with the surfaces of the plates, removing it, heating 1t to drive ofi the absorbed water, and re-ap+ plying it continuously to fresh plate-sur faces.

The following is a description by way of example of one method of carrying this invention into eifectie After the steps of hot rolling in the mills, shearing and opening, the plates are subjected to the steps of black packing, black annealing and throwingxout (1. e. separating the plates).

Pickling and drying are then effected and'the accom anying drawing lllustrates diagrammatica y one suitable form of apparatus for this purpose The separated plates are placed on a table A in a pile. An oscillating arm B provided with a sucker C (connected with a suitable source of suction) is so pivoted that it can lift the plates one at a time from the nip of apair of rubber-covered feed rolls. G and pass-between water spra s H so that they are swilled to remove aci The rolls G, of hich there are several pairs, act in conjunction-with a guide 9 to direct the plates into -a water bath K through which they are conveyed by a seclivered by further ers L.

0nd arrangement of .feed wheels F and derolls G to drying roll- The dryin rolls L are covered on their external sur ace with a thick layer Z of porous" absorbent material, such as felt.

Through a suitable trunnion at; one end steam is admitted to the interiorof the rolls and the felt is maintained at a temperature Their mec anical aconsiderable distance.

of about 100 C. After passing through two pairs of drying rollers L, the plates enter a further'pair of feed rolls 'M and are deposited ona conveyor N which removes them from the apparatus;

In operation the oxidation upon the plates is removed by the acid. The plates are then swilled.. In' the water-bath they are Washed and the water contains a small percentage of some chemical which has the property of precipitating colloidal ferric hydroxide, such e. 'as potassium bichromate. On entering t e drying rolls their moisture is removed by absorption before it has had any opportunity to cause oxidation of the plates.

The moisture is then evaporated from the felt by reason of the heat of the latter, and

the felt oncoming again into contact with a plate, after a-revolution of the drying roll L, is sufficiently dry to continue to absorb moisture effectively. The plates are .thus dried without ever reaching a temperature as high as 100 C. and without any evaporation taking place from. them."

Various modifications may be made in the drying arrangements, for example instead of simply having rollers covered with absorbent material, a band of such material may be caused to pass over a pair or more of rollers-on each side of the plates and the bands maybe in: contact with the plates for Instead of felt, other absorbent material may be used and this maybe in the form of a rope wound closely around the drying rolls. The means for feeding the plates through the baths E and K may vary. Thepickling bath E isheated as usual, and any desired or suitable means for this purpose or for heating the drying rolls may be employed. In practice the machine would be made sufiiciently wide to receive a number of plates simultaneously side by side.

What I claim as my invention and desire to secure by Letters Patent 'is 1. A rocess for the manufacture of tinplate w ich com rises in combination the stages of hot rol ing the plates, thereafter black annealing them, then black pickling and swilling them, thereafter drying them in such manner that they do not reach a temperature substantially exceedin 100 (1,

thereafter passing the lates as timed to the cold-rolling plant an cold rolling them, then pre aring the plates for tinning, and tinning t em.

2. A rocess for the manufacture .of tinplate -w ich com rises in. combination the stages of" hot rol ing the plates, thereafter blackannealing them, then black pickling and swilling them, thereafter drying them by bringing water-absorbent material into contact with the surfaces of the plates, removing it, heating it to drive off the absorbed water and reapplying it continuously to fresh plate-surfaces, thereafter passing the plates as dried to the cold-rolling plant and cold rolling them, then preparing the.

plates for tinning, and tinning them.

3. A process for the manufacture of tin-- plate which comprises in combination the stages ofhot-rolling, shearing and opening plate wiich comprises in combination the stages of hot-rolling, shearing and opening the plates, thereafter, without intermediate operation, black annealing them, then black pickling and swilling them, thereafter drying them by bringing water-absorbent material into contact with the surfaces of the plates, removing it, heating it to drive off the absorbed water and rea plyin it continuously to fresh plate-sur aces, t ereafter passing the plates as dried to the cold-rollmg plant and cold rolling them, then preparing the plates for tinning,

them. 1

5. A process for the manufacture of tinplate which comprises in combination the stages of hot-rolling the plates, thereafter black annealing them, then black pickling and swilling them, treating the plates with a wash solution containing a solute which precipitates colloidal ferric hydroxide, thereafter drying them in such manner thatthey do not reach a temperature substantially exceeding 100 (1, thereafter passing the plates as dried to the cold-rolling plant and cold rolling them,then preparing the plates for tinning, and tinning them.

6. A process for the manufacture of tin-.. plate which comprises in combination the stages of hot-rolling the plates, thereafter black annealing them, then black pickling and swilling them, treating the plates with a wash solution containing a solute which preci itates colloidal ferric hydroxide, therea' ter drying them by bringing water-absorbent material into contact with the surfaces of the plates, removing it, heating it to drive ofi the absorbed water and re-applying it continuously to fresh plate-surfaces, thereafter passing the plates as dried to the cold-rollin plant and cold rolling them, then preparing the plates for tinning, and tinning them.

7. A process for the manufacture of tinplate which comprises in combination the stages of hot-rolling, shearing and opening the plates, thereafter, without any intermediate operation, black annealing them, then and tinning black pickling and swill'ing them, treating the plates with a wash solution containing a solute which precipitates colloidal ferric hydroxide, thereafter drying them bybringing water-absorbent material into contact with the surfaces of the plates, removing it, heating it to drive off the absorbed water and re-applying it continuously to fresh platesurfaces, thereafter passing the plates as dried to the cold-rolling plant and cold rolling them, then preparing the plates for tinning, and tinning them.

8. A process for the manufacture o'f'tinplate which com arises in combination the stages of hot-rolling, shearing and opening the plates, thereafter, without any intermedate operation, black annealing them, then black pickling and swilling them, treating the plates with a wash solution containing potassium bichromate, thereafter drying them by bringing water-absorbent material into contact with the surfaces of the plates, removing it, heating it to drive off the absorbed Water and re-applying it continuously to fresh plate-surfaces, thereafter passing the plates as dried to the cold-roll- .ing plant and cold-rolling them, then preparing the plates for tinning, them.

9. A rocess for the manufacture of tinplate wiich comprises in combination the stages of hot-rolling the plates, thereafter black annealing them, then black pickling and swilling them, thereafter bringing theni, into contact with absorbent drying webs supported upon rollers which are internally steamheated, thereafter passing the plates as dried to a cold rolling plant and coldand tinning rolling them, preparing the plates for tinning, and tinning them.

10. A process for the manufacture. of tinplate which comprises in combination the stages of hot-rolling, shearing and opening the plates, thereafter, without any interme' diate operation, black annealing them, then black-pickling and swilling them, treating the plates with a wash solution containing a solute which precipitates colloidal ferric hydroxide, thereafter bringing them into contact with absorbent drying webs supported upon rollers which are internally steamheated, thereafter passing the plates as dried to a cold-rolling plant and cold-rolling them, preparing the plates for tinning, and tinning them.

11. Apparatus for drying sheet metal which comprises in combination means to receive plates and feed them automatically in a direction parallel to the plate surfaces and continuous drying webs of water absorbent material so disposed as to be in con tact with both sides of the plates when in use to absorb moisture therefrom, means to move the drying webs so as to present continuously a fresh part of the web surfaces lift) thereto and mezins to heat the webs te altemperature sufiicient to evaporate 'absorbedi moisture therefrom while out "of contact with the plates.

' 12. In apparatus for drying sheet metal the combination of feed rollers to advance the plates through the apparatus anti rocovered on their-exteriorsurface with yielding' water-absorbent material.

In testimony whereof I afiix my signature.

GAVIN MURE HARRIS. 

